Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 281638

Area Forecast Discussion
National Weather Service Lincoln IL
1038 AM CST Mon Nov 28 2016

Issued at 1026 AM CST Mon Nov 28 2016

Showers and scattered thunderstorms dominated the mid morning
hours over Central Illinois. An extensive storm system is
resulting in several rounds of precip in the region. More rain is
developing to the SW and spreading into the area this morning and
will continue across most of Central Illinois throughout the day.
Although there will be periodic breaks...showers and blustery
winds are going to be the norm throughout the most of the day.
Some minor updates have been made, but no large scale changes are
expected throughout the day.


.SHORT TERM...(Today and tonight)
ISSUED AT 328 AM CST Mon Nov 28 2016

A large and slow moving storm system will continue to impact central
and southeast Illinois through the period and beyond. The deep 976
mb surface low is currently centered over eastern South Dakota and
will move little over the next 24 hours. A tight pressure gradient
to the east of this system is providing gusty southerly winds across
the area, and these should persist through the period, with gusts to
40 mph possible at times.

While showers are moving out of the forecast area early this
morning, the break in the rainfall will be short lived. A second
strong short wave will help produce another round of showers from
midday today into this evening. The short wave that brought us
rainfall late yesterday to now tracked west of the forecast area,
while today`s wave is progged to track directly across the forecast
area. This track is supportive of better dynamics locally, as well
as steeper lapse rates. These factors favor including a mention of
thunder with today`s rainfall. The track of the wave will also
provide more of a gradient of QPF, with the eastern half of the
forecast area receiving more significant rainfall totals than the
west. Southeast Illinois is likely to see rainfall totals in excess
of 1 inch before the rain ends later tonight.

Much like in the past 24 hours, the next 24 hours will see
relatively small diurnal temperature ranges due to the clouds and
rainfall. Expect highs today in the lower 50s and lows tonight in
the 40s, both of which are well above normal for late November.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 328 AM CST Mon Nov 28 2016

The 00Z forecast models continue to show a fairly nice late fall day
on Tuesday over central and southeast IL, as a partly to mostly
sunny day unfolds. Breezy southerly winds bringing milder highs
in the upper 50s and lower 60s. MET guidance even as warm as 65F
at Jacksonville and Lawrenceville and if we get enough sunshine,
that could be achievable. Large low pressure system over the upper
MS river valley Tuesday will pivot a short wave trof and cold
front eastward across IL Tuesday night. The 00Z NAM model
continues to have some light qpf over areas along and north of a
Rushville to Bloomington line, where SPC day2 again shows general
risk of thunderstorms. Plume of steep mid level lapse rates will
advect over central IL Tue evening and be over a somewhat unstable
air mass with MUCAPES of several hundred J/kg. Have added slight
chance of showers/thunderstorms to northern CWA Tue evening.

Large upper level low/trof tracks east across the northern Great
Lakes Wed and Wed night and into southern Quebec and northern New
England on Thursday. This will bring more low clouds (especially
north of I-70) and cooler temperatures. Brunt of light rain/snow
showers, should mostly stay north of central IL, but get closest to
far northern counties Wed afternoon and early Wed evening. Highs Wed
range from mid 40s over IL river valley, to lower 50s in southeast
IL. Highs Thu in the lower 40s, with Lawrenceville near 45F. About 2
degrees cooler on Friday with highs in the upper 30s from I-74 north
and lower 40s south. Seasonably cool temperatures to continue Friday
and this weekend with dry weather Friday and Saturday. Some big
differences continue between the ECMWF and GFS model solutions on
Sunday, with ECMWF showing large area of qpf lifting northward over
IL while GFS model is dry and colder over IL. Made no changes to the
blended model guidance due to lack of confidence in forecast that
far out. Have slight chances of light rain/snow over southeast IL
overnight Sat night and across most of area on Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 542 AM CST Mon Nov 28 2016

A strong storm system will impact the central Illinois terminals
through the 12Z TAF valid time. Gusty southerly winds are expected
through most of the period. Widespread MVFR conditions are likely
to start the day, but these will degrade to IFR as another area of
showers moves through the region from midday into the evening
hours. An isolated thunderstorm can`t be ruled out, but expected
coverage is too low to carry in the terminals at this time. Conditions
will improve later tonight as the rainfall moves out of the area.




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